Interaction Between Disk Lubricants and Solvents in the Dip-Coating Process

Abstract

It has been reported earlier that, keeping all other factors fixed, the disk performance could vary significantly depending on the choice of solvent used in the dip-coating process. We surmised that the difference in the ability of solvent to disrupt the intermolecular hydrogen bonding between hydroxyl units of Z-dol or Z-tetraol would lead to a different structure or arrangement of the lubricant molecules as the solvent evaporated in the dip-coating process. Using proton NMR and IR spectroscopy, four solvents, hexafluorobenzene, Vertrel-XF, HFE7100, and FC72, were examined for their ability to disrupt the hydrogen bonding of Z-dol and Z-tetraol. The study has revealed that the said ability increases in the order of FC72 < HFE7100 < hexaflurobenzene < Vertrel-XF. Z-dol molecules, for example, are completely separated from each other in Vertrel-XF, but maintain their intermolecular hydrogen bonding in FC72. It has also revealed an extraordinary formation of complexoid between HFE molecules and Z-tetraol with MW n of~2000. The complexoid has a specific stoichiometry of (Z-tetraol) n (HFE)~15 n and is not miscible with HFE. The formation of such complexoid was not observed for Z-tetraol of larger MW n ( ‡3000).

Oxidation of Disk Lubricants: an NMR Study

“…The peak due to hydroxyl protons shifts up-field on heating. The hydroxyl proton is known to shift up-field as the probability to mutually hydrogen-bond decreases 5) . Most intriguingly, when Z-tetraol that had been heated at 150 o C for 10 days was subsequently heated at 200 o C for two days, totally different F-19 and C-13 spectra were observed.…”

Z-dol and carbon overcoat: the bonding mechanism

“…Needless to say, the value of bonded fraction varies depending on the solvent used. For PFPE lubricants with OH-containing end-groups, a solvent known to disrupt the hydrogen bonding should be used in order to obtain a meaningful value of bonded fraction [10].…”

Dip-Coating of Patterned Organic Semiconductor Films

“…Therefore, the undesired intermixing of solution-prepared organic films with previous or postal organic layer can be avoided. A variety of parameters such as solvent [10] , concentration [11] , temperature [12] and surfactant [13] have been studied for dip-coating processes, however, film patterning of these films is rarely further investigated.…”